Biomedical subjects
W F House
Publications and source records attributed to W F House.
Cochlear implant histopathology.
Twenty-two temporal bones and one brain stem from 13 cochlear implant patients were examined histologically. Sixteen temporal bones had undergone one or more implant procedure. Results of analysis suggested that the ganglion cells were the responding elements to the implant and that useful auditory sensation could result from as few as 10 percent of the normal number of ganglion cells. All implanted bones exhibited varying amounts of fibrosis (some ossified) in the basal turn of the cochlea and beyond in some cases. Usually there was damage to the surviving elements of the organ of Corti and the dendrites throughout the extent of the electrode insertion. However, the ganglion cell population was not affected. Prolonged electrical stimulation (up to 14 years) did not affect ganglion cell survival in three cases, and had no effect on the cochlear nerves in two cases or on cochlear nuclei in one case.
Cochlear implants in children: past and present perspectives.
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Implementing a cochlear implant team in private practice or academic setting.
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Inner ear morphologic changes resulting from cochlear implantation.
Insertion of electrodes into the cochlea can damage the spiral ligament, organ of Corti, osseous spiral lamina, and dendrites. The amount of damage depends on the method of insertion and the amount of surgical trauma. Damage is limited to the area immediately adjacent to the electrode. Damage in the cochlea and prolonged electrical stimulation do not affect ganglion cell population. The ganglion cell population responds directly to the electrical stimulus. Examination of three auditory nerves from three cases and the cochlear nuclei from one case also reveals no effect of prolonged electrical stimulation.
Auditory brain stem implant: effect of tumor size and preoperative hearing level on function.
The auditory brain stem implant is an investigational device designed to provide hearing sensations to patients without functioning auditory nerves. We analyzed results from 17 implants in 15 patients to determine if tumor size or preoperative hearing level might be related to proper device function. We found no significant correlation between preoperative hearing level or tumor size and device function. We also found no significant correlation between preoperative hearing level and tumor size in these 15 patients.
Investigator differences in the cochlear implantation of children.
Eight investigational sites are involved in clinical trials of the 3M/House cochlear implant for children. Statistical analyses have been performed to examine differences between investigators in patient populations selected for implantation and in the results achieved. Important characteristics of the subjects from different investigational sites were compared for House, Maddox, and all "others" combined. There were no differences between investigators in sex, age at surgery, or duration of deafness of the children enrolled in the study. For age at onset, House and Others had higher proportions of postlingually deaf subjects than Maddox (16% for House and 18% for Others, compared with less than 2% for Maddox). However, all investigators had some subjects in every category: postlingual, prelingual, and congenital. Auditory discrimination and speech production scores for subjects from the three groups were compared using analysis of variance techniques. A few interaction effects between time interval and investigator indicated that not all investigator groups performed similarly over time for all measures. However, postimplant scores were always significantly higher than preimplant scores for all investigators. Differences that did occur appeared to be attributable to differences in subject characteristics.
Re-evaluation of the role of the human endolymphatic sac in Menière's disease.
The role of endolymphatic sac (ES) dysfunction in the etiopathogenesis of Meniere's disease has remained controversial since the early 1900s. The first reports of the ultrastructural (transmission electron microscopy, TEM) pathology of the human ES in Meniere's disease have been published only in the last decade. These studies have been based on biopsies of the extraosseous (intradural) ES and in no cases has the TEM appearance of the intraosseous ES been described. Likewise the control material used has been from biopsies of extraosseous ES taken from patients with acoustic schwannomas. To date, no reports have compared the ultrastructure of the intrasosseous ES from normal control patients to patients with Meniere's disease. Since the intraosseous ES is believed to be the most active portion of the entire ES, studies were made of the ultrastructure of ten normal interosseous human ESs fixed immediately after death and obtained at autopsy (control material). Fourteen patients undergoing translabyrinthine (TL) neurotologic procedures (10, TL resection of acoustic schwannoma; 4, TL eighth cranial nerve section for Meniere's disease) had the entire vestibular aqueduct, containing the endolymphatic duct and the intraosseous ES, removed and processed for TEM. The roles of the epithelium, subepithelial space, and vasculature were morphologically studied to evaluate possible ES pathology in Meniere's disease and in patients with acoustic schwannoma. Wide anatomic variation in the distribution and density of the subepithelial connective tissue was observed in all groups. There was no difference in the TEM appearance of the intraosseous ES from normal controls and patients with eighth nerve schwannoma, nor was there any difference in the ES collagen deposition in patients with Meniere's disease. The ESs from two patients with Meniere's disease showed evidence of abnormal glycoprotein metabolism; one with possible hypersecretion and one with possible alteration of degradation of resorbed glycoprotein. The results of this preliminary study suggest that "perisaccular fibrosis" of the intraosseous ES was not a pathologic feature in these four cases of Meniere's disease and that alteration of ES glycoprotein secretion/resorption may be of etiopathologic significance.
Diagnosis and treatment of arachnoid cysts of the posterior fossa.
Arachnoid cysts of the posterior fossa are rare. When arachnoid cysts are encountered, the presenting symptoms are frequently otologic, with hearing loss and imbalance occurring commonly. Three cases are presented with a previously unreported otologic symptom, that of bilateral hearing loss, which in one case was fluctuant. None of the patients had the common symptoms of unilateral hearing loss and headache. With the advent of computed tomography and magnetic resonance imaging, these cysts may be readily identified, usually with diagnostic imaging alone. Unfortunately there is often a delay in diagnosis because of the vague and fleeting nature of the symptoms. Because no single diagnostic symptom pattern is able to characterize all cases, it is believed computed tomography or magnetic resonance imaging or both are indicated in patients with long-standing otologic complaints--even in the absence of unilateral symptoms. Treatment of posterior fossa arachnoid cysts primarily consists of surgical procedures designed to decompress the cyst. In this series, treatment with diuretics alone resulted in improvement of symptoms during several years of followup, with no evidence of enlargement of the cysts.
Hearing improvement after acoustic tumor removal.
Hearing improvement after removal of an acoustic tumor is an uncommon occurrence. Hearing improvement was observed in 8.5% of acoustic tumor removals performed using the middle fossa approach in an attempt to preserve hearing. Improvement in speech discrimination occurred most frequently and was of greatest magnitude compared with changes in the speech reception threshold or pure-tone average. No preoperative factors were predictive of postoperative hearing improvement. Findings support the conclusion that candidates for hearing preservation surgery should be chosen on the merits of their existing preoperative hearing and not on the basis of anticipated improvement.
Hearing preservation after acoustic tumor removal: long-term results.
This report examines the durability of preserved postoperative hearing in 25 middle fossa acoustic tumor patients with a minimum follow-up of 3 years. The mean follow-up time for this group was more than 8 years, with a maximum of almost 20 years. The initial postoperative audiogram was compared to the most recent audiogram for each patient, with change in the nonoperated ear serving as the control. Fourteen of the patients (56%) had a significant loss of the preserved hearing in the operated ear over time. The mean loss of speech discrimination was 25%, and the mean loss of speech reception threshold was 12 dB. Only one of the 14 patients had a similar loss in the contralateral ear. No recurrent tumors were identified. Good preoperative hearing is an obvious criterion for selection of candidates for hearing preservation surgery. Results of this study emphasize that a good initial postoperative hearing level is necessary to offset the potential deterioration of hearing that may occur over time.
Middle fossa decompression of the internal auditory canal in acoustic neuroma surgery: a therapeutic alternative.
Unilateral acoustic neuromas in only-hearing ears and bilateral acoustic neuromas (NF-2) are separate entities, but both pose a common problem because surgical removal has the potential to leave the patient totally deafened. A middle fossa decompression of the internal auditory canal (IAC) was performed in 8 patients (5 with NF-2 tumors and 3 with neuromas in an only-hearing ear). In 5 of the 8, the speech discrimination scores at the 6-month follow-up were better than preoperative scores. After 6 months, however, hearing regressed at variable rates. Although not a definitive therapeutic treatment, decompression of the IAC appears to improve and perhaps prolong useful hearing, which gains valuable time for rehabilitation. Rigid follow-up by computed tomography scans or magnetic resonance imaging is essential.
[Cochlear implants: histological data].
We have performed a histological examination of the pars petrosa of 13 implanted patients. Morphological data were confronted with the clinical findings. The results of this study show that the nerve elements stimulated by the electrode are the cells of the spiral ganglion, and that a small number of ganglionic cells, as few as 10% of the normal figure, is compatible with auditory perception by electrical stimulation. Furthermore, all the implanted pars petrosa were the seat of a fibrosis and neo-ossification reaction around and sometimes even beyond the tip of the electrode. The trauma caused by the insertion of the electrode into the cochlea involved the sensorial cells of the organ of Corti and the dendritic populations in the lamina spiralis, but the cells of the spiral ganglion were spared. Prolonged electrical stimulation (14 years in 1 case) does not appear to have any deleterious effect on the survival of the spiral ganglion, of the cochlear nerve or of the cochlear nucleus.
Sex hormone receptors in acoustic neuromas.
We performed quantitative assays for estrogen, progesterone, and testosterone receptors in 19 acoustic neuroma specimens from ten men and nine women. No patient received preoperative or intraoperative glucocorticoids, mineralocorticoids, or sex hormones. All tumors were unilateral and removed by the translabyrinthine approach. No tumor specimen was positive for estrogen or testosterone receptors. Three of ten men and seven of nine women had tumors positive for progesterone receptors (10 fmol/mg cytosol protein or greater). This between-sex difference was of borderline significance by the Mann-Whitney U test (p = 0.08). This finding indicates the need for further investigations of endocrinologic therapy as a possible treatment of acoustic neuromas.
Acoustic tumor surgery. Prognostic factors in hearing conversation.
Preoperative selection criteria for hearing conservation surgery in patients with acoustic tumors continues to be unresolved. The level of hearing that is worth saving is still debatable. However, most acoustic tumor surgeons agree that hearing preservation is less likely the larger the tumor. We reviewed the results of 106 middle fossa acoustic tumor removals with attempted hearing preservation. Measurable postoperative hearing remained in 59% of 97 cases analyzed for postoperative hearing results. Tumor size, preoperative auditory brain-stem response, and preoperative electronystagmography were found to be useful in predicting successful postoperative hearing preservation. We found no correlation between the level of preoperative hearing and our ability to preserve measurable postoperative hearing. A new classification system is proposed for reporting hearing results after acoustic tumor surgery. It is based on functional hearing results and we believe it is simpler than previously proposed systems.
Open-set speech recognition in children with a single-channel cochlear implant.
We evaluated the ability of profoundly deaf children using the 3M/House single-channel cochlear implant to understand speech without the aid of speechreading. Fifty-one implanted children over the age of 5 years, who had sufficient cognitive and language skills, were tested using word and sentence stimuli presented in an open-set, auditory-only mode. Fifty-two percent of the children demonstrated some open-set performance on word identification, while 41.5% did so on sentence comprehension. Children who scored open-set had a shorter duration of deafness than those who did not. A larger proportion of children using oral communication demonstrated open-set speech recognition than those using total communication. A multiple regression analysis indicated that communication method accounted for the largest proportion of variability in performance on both the word and sentence tasks. Children achieving open-set auditory recognition, however, included both those using oral communication and those using total communication, children deafened by meningitis and those born deaf, and children with varying durations of deafness.
The narrow internal auditory canal in children: a contraindication to cochlear implants.
We suggest a new explanation for the lack of auditory response to electric stimulation in children with cochlear implants: the very narrow internal auditory canal, 1 to 2 mm in diameter, and the probable absence of the cochlear nerve. This defect can be seen on high-resolution computed tomographic x-ray studies and may represent aplasia of the auditory-vestibular nerve. We report on eight children with this anomaly, three of whom have received implants and failed to respond with a sensation of sound. Identification of this problem on screening x-ray films is a contraindication to cochlear implantation for auditory stimulation.
Middle fossa acoustic tumor surgery: results in 106 cases.
Although the middle cranial fossa approach has been used less frequently in recent years than in the past, it continues to be a useful technique for the removal of small acoustic tumors with possible hearing preservation. The approach provides complete exposure of the contents of the internal auditory canal, thus allowing positive facial nerve identification and facilitating total tumor removal. This paper reports the results of 106 middle fossa acoustic tumor removals over a 25-year period. Measurable postoperative hearing remained in 59% of cases. In 89% of cases, normal or near-normal postoperative facial nerve function was obtained. Total tumor removal was achieved in 98% of cases. Preoperative selection criteria are discussed, and postoperative complications are reported.